Recently, a great deal of interest is focused on nitride-based light emitting diodes (LEDs) and lasers that emit light in the blue and deep ultraviolet (UV) wavelengths. These light emitting devices may be capable of being incorporated into various applications, including solid-state lighting, biochemical detection, high-density data storage, and the like. However, to date, the performance of nitride-based light emitting diodes and lasers quickly worsens as the radiation wavelength is reduced into the ultraviolet range.
A difficulty in developing a deep UV LED is a deficient hole injection. In particular, Magnesium (Mg) is the most successful acceptor, and is therefore commonly used for p-type Gallium (Ga) Nitride (N) layers. The room-temperature activation energy for such a layer can be as high as two-hundred fifty milli-electron Volts (meV), and increases roughly linearly with the Aluminum (Al) molar fraction in AlGaN alloys. However, a large acceptor binding energy results in a deficient hole injection. This is particularly true for a deeper UV LED, in which a higher Al molar fraction is required.
Regardless, deep UV LEDs and UV LED lamps have recently been developed that provide a dramatic improvement of output power and efficiency over previous deep UV devices and lamps, and may provide for a large UV power density. However, standard UV laser diodes remain difficult and expensive to manufacture, and deep UV lasing has not been achieved.
Laser structures have been manufactured using inorganic and/or organic laser structures. For example, an illustrative laser structure may include Aluminum-Gallium-Indium-Nitride (AlGaInN)-based solid state LEDs that pump an active media. The active media can be an inorganic structure, such as an AlGaInN or AlGaN (with or without traces of In)-based quantum well, quantum wire, or quantum dot laser structure or may be an organic structure. Organic LEDs have demonstrated long life times and high brightness, and as a result, have been utilized in some commercial applications. Amplified spontaneous emission has been observed in, for example, spiro-linked materials, including Spiro-44, shown and described in U.S. Pat. No. 5,840,217. However, the reported wavelengths for an optically pumped organic laser have been 377 nanometers or longer, barely within the UVA subregion of the UV spectral region. To date, electrically pumped organic lasing has not been demonstrated.
In view of the foregoing, a need exists to overcome one or more deficiencies in the related art.